TP53 gene protects elephants from cancer

Despite being much larger than humans, elephants have a much lower rate of cancer thanks to possessing a larger number of TP53 genes.

Elephants are animals that rarely get cancer. Photo: Wikipedia.

According to the Washington Post, the death rate of elephants due to cancer is about 4.8%, while the rate in humans is up to 11-25%. This is quite strange because elephants have 100 times more cells than humans, while the two species have a similar average life span of about 70 years. Normally, the more cells, the higher the chance of the cells mutating and turning malignant, meaning that elephants should have a higher rate of cancer than humans. But the reality is quite the opposite.

For decades, scientists have wondered why elephants and large mammals are less likely to get cancer than small mammals. The question is known as "Peto's paradox."

In an article published in the Journal of the American Medical Association at the end of July, a research team led by Joshua Schiffman, an oncologist at the Huntsman Cancer Institute in the US, pointed out that African elephants have 20 copies (40 alleles) of the TP53 gene. TP53 produces a protein that can prevent tumors. Humans have only one copy (2 alleles) of this gene. Scientists call TP53 "the guardian of the genome".

Of the 20 copies of the TP53 gene, 19 are retrogenes (DNA created from RNA by reverse transcription). These extra genes were selected through elephant evolution to resist cancer.

To find out how the TP53 gene works, the team collected white blood cells (leukocytes) from elephants and humans. They then exposed the leukocytes to radiation, which causes the DNA double helix to break.

The team predicted that elephant cells containing more TP53 genes would be able to repair themselves faster than human cells after being exposed to radiation. But the results were completely different. The number of elephant cells that died was much higher than that of human cells. The TP53 gene caused the mutated cells to self-destruct, not allowing them to transform into cancer cells.

"If you kill the damaged cells, they disappear and cannot become cancer cells. This could be an effective approach to fighting cancer instead of trying to stop a mutated cell from dividing and not being able to repair itself," Schiffman said.

According to VNE